Fig. 1.

Schematic view of CoQ biosynthesis pathway in a eukaryotic cell. (A) The isoprene units are derived from the mevalonate pathway and polymerized by PDSS1/PDSS2 heterotetramer in the cytoplasm. (B) COQ2 links the polyprenylated tail and the qui-none head (4-hydroxybenzoate) in mitochondria. (C) The rest of the CoQ biosynthesis reactions take place in the matrix side of the mitochondrial inner membrane (yellow box), consisting of sequential modifications of the aromatic ring. Coq6 and Coq7 are hydroxylases; Coq3 andCoq5 are methylases; Coq4, Coq8, Coq9, and Coq10 are proteins with regulatory functions. Adapted from [27]; used with permission